The last time I went deer hunting, my friend had a vertical rack mounted between the front seat of his old Toyota 4x4 pickup truck. It held two rifles side by side, resting vertically on their recoil pads, and held in place with velcro straps.
"Freedom had been hunted round the globe; reason was considered as rebellion; and the slavery of fear had made men afraid to think. But such is the irresistible nature of truth, that all it asks, and all it wants, is the liberty of appearing." --Thomas Paine, Rights of Man, 1791